D.C Motor: [ ISRO,DRDO,DMRC,SAIL, ODNANCE, HAL, WBSEDCL, RAILWAY & Others competitive] DC Motor MCQ Questions And Answers
31. Torque developed by a D.C. motor depends upon…………
(a) magnetic field
(b) active length of the conductor
(c) current flow through the conductors
(d) all above factors
Ans: d
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32. D.C. shunt motors are used for driving…………
(a) trains
(b) cranes
(c) hoists
(d) machine tools
Ans: d
33. In a manual shunt motor starter…………
(a) over load relay is connected in series and no volt relay in parallel with the load
(6) over load relay is connected in parallel and no volt relay in series with the load
(c) over load relay and no volt relay are both connected in series with the load
(d) over load relay and no volt relay are both connected in parallel with the load
Ans: a
34. Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator?
(a) Providing laminations in armature core
(b) Providing laminations in stator
(c) Using non-magnetic material for frame
(d) Using material of low hysteresis co-efficient for armature core material
Ans: d
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35. Why are the D.C. motors preferred for traction applications?
(a) Torque and speed are inversely proportional to armature current
(b) Torque is
proportional to armature current
(c) Torque is
proportional to square root of armature current
(d) The speed
is inversely proportional to the torque and the torque is proportional to
square of armature current
Ans: d
36. Which of the following motors is usually used in house-hold refrigerators?
(a) D.C. shunt motor
(b) D.C. series motor
(c) Single phase induction motor (split phase start or induction run motor)
(d) Reluctance motor
Ans: c
37. Which of the following motors is most suitable for signalling devices and many kinds of timers ?
(a) D.C. shunt motor
(b) D.C. series motor
(c) Induction motor
(d) Reluctance motor
Ans: d
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38. Which motor should not be started on no-load?
(a) Series motor
(b) Shunt motor
(c) Cumulatively compounded motor
(d) Differentially compounded motor.
Ans: a
39. Ward-Leonard control is basically a
(a) voltage control method
(b) field divertor method
(c) field control method
(d) armature resistance control method
Ans: a
40. For constant torque drive which speed control method is preferred?
(a) Field control
(b) Armature voltage control
(c) Shunt armature control
(d) Mechanical loading system
Ans: b
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